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Developmental Biology Aug 2010Tricho-dento-osseous (TDO) syndrome is an autosomal dominant disorder characterized by abnormalities in the thickness and density of bones and teeth. A 4-bp deletion...
Tricho-dento-osseous (TDO) syndrome is an autosomal dominant disorder characterized by abnormalities in the thickness and density of bones and teeth. A 4-bp deletion mutation in the Distal-Less 3 (DLX3) gene is etiologic for most cases of TDO. To investigate the in vivo role of mutant DLX3 (MT-DLX3) on dentin development, we generated transgenic (TG) mice expressing MT-DLX3 driven by a mouse 2.3 Col1A1 promoter. Dentin defects were radiographically evident in all teeth and the size of the nonmineralized pulp was enlarged in TG mice, consistent with clinical characteristics in patients with TDO. High-resolution radiography, microcomputed tomography, and SEM revealed a reduced zone of mineralized dentin with anomalies in the number and organization of dentinal tubules in MT-DLX3 TG mice. Histological and immunohistochemical studies demonstrated that the decreased dentin was accompanied by altered odontoblast cytology that included disruption of odontoblast polarization and reduced numbers of odontoblasts. TUNEL assays indicated enhanced odontoblast apoptosis. Expression levels of the apoptotic marker caspase-3 were increased in odontoblasts in TG mice as well as in odontoblastic-like MDPC-23 cells transfected with MT-DLX3 cDNA. Expression of Runx2, Wnt 10A, and TBC1D19 colocalized with DLX3 expression in odontoblasts, and MT-DLX3 significantly reduced expression of all three genes. TBC1D19 functions in cell polarity and decreased TBC1D19 expression may contribute to the observed disruption of odontoblast polarity and apoptosis. These data indicate that MT-DLX3 acts to disrupt odontoblast cytodifferentiation leading to odontoblast apoptosis, and aberrations of dentin tubule formation and dentin matrix production, resulting in decreased dentin and taurodontism. In summary, this TG model demonstrates that MT-DLX3 has differential effects on matrix production and mineralization in dentin and bone and provides a novel tool for the investigation of odontoblast biology.
Topics: Animals; Bone and Bones; Caspase 3; Dentin; Ectodermal Dysplasia; Humans; Male; Mice; Mice, Transgenic; Odontoblasts; Odontogenesis; Sequence Deletion; Tooth
PubMed: 20510228
DOI: 10.1016/j.ydbio.2010.05.499 -
Archives of Oral Biology Jan 2020Description of the odontoblast lifecycle, an overview of the known complex molecular interactions that occur when the health of the dental pulp is challenged and the... (Review)
Review
OBJECTIVE
Description of the odontoblast lifecycle, an overview of the known complex molecular interactions that occur when the health of the dental pulp is challenged and the current and future management strategies on vital and non-vital teeth.
METHODS
A literature search of the electronic databases included MEDLINE (1966-April 2019), CINAHL (1982-April 2019), EMBASE and EMBASE Classic (1947-April 2019), and hand searches of references retrieved were undertaken using the following MESH terms 'odontoblast*', 'inflammation', 'dental pulp*', 'wound healing' and 'regenerative medicine'.
RESULTS
Odontoblasts have a sensory and mechano-transduction role so as to detect external stimuli that challenge the dental pulp. On detection, odontoblasts stimulate the innate immunity by activating defence mechanisms key in the healing and repair mechanisms of the tooth. A better understanding of the role of odontoblasts within the dental pulp complex will allow an opportunity for biological management to remove the cause of the insult to the dental pulp, modulate the inflammatory process, and promote the healing and repair capabilities of the tooth. Current strategies include use of conventional dental pulp medicaments while newer methods include bioactive molecules, epigenetic modifications and tissue engineering.
CONCLUSION
Regenerative medicine methods are in their infancy and experimental stages at best. This review highlights the future direction of dental caries management and consequently research.
Topics: Dental Caries; Dental Pulp; Dental Pulp Exposure; Humans; Immunity, Innate; Odontoblasts; Regeneration
PubMed: 31710968
DOI: 10.1016/j.archoralbio.2019.104591 -
Connective Tissue Research 2002The inherited dentin defect dentinogenesis imperfecta (DI), while clinically obvious in osteogenesis imperfecta (OI) Types IB and IC, II, III, and IVB, is now thought to...
The inherited dentin defect dentinogenesis imperfecta (DI), while clinically obvious in osteogenesis imperfecta (OI) Types IB and IC, II, III, and IVB, is now thought to be present in all children with OI, in a continuum from minimal to severe dentin pathology. This collaborative study further clarifies the structural and ultrastructural dentin changes in the teeth of OI children with clinically obvious DI, and attempts to explain these in terms of odontoblast dysfunction. Collaborative studies were carried out in Melbourne, Australia, and Strasbourg, France, using light and polarized-light microscopy, scanning and transmission electron microscopy (SEM, TEM), selected-area diffraction (SAD), and x-ray spectroscopy (EDX). These showed structurally normal enamel (but containing long and broad lamellae) and a normally scalloped dentino-enamel junction (DEJ), but severe pathologic changes in the dentin. An initial narrow band of normal-appearing dentin tubules (including the mantle layer) ceased abruptly and was replaced by a wavelike laminar zone parallel to the DEJ with occluded tubules. Multiple parallel channels of 5-10 microns diameter were present at right angles to the DEJ indenting this zone, some terminating in retro-curved "processes." The abnormal dentin containing these channels almost completely occluded the pulp chamber. The structural and ultrastructural changes seen can be explained on the basis of the collagen defect in OI resulting in odontoblast dysfunction, which produces a distinct phenotype and one that is different from that in bone.
Topics: Child; Dentin; Dentinogenesis Imperfecta; Humans; Microscopy, Electron; Microscopy, Electron, Scanning; Odontoblasts; Osteogenesis Imperfecta
PubMed: 12489189
DOI: 10.1080/03008200290001005 -
Dental Materials : Official Publication... Jun 2018To screen the effect of two compounds, chlorhexidine diacetate (CHX) and epigallocatechin-gallate (EGCG), on the levels of cytokines produced by odontoblast-like cells...
OBJECTIVE
To screen the effect of two compounds, chlorhexidine diacetate (CHX) and epigallocatechin-gallate (EGCG), on the levels of cytokines produced by odontoblast-like cells (MDPC-23).
METHODS
Cells were seeded at 24h and 48h with serial dilution of the compounds to determine cell metabolic activity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (n=3). Cells with no compound treatment were used as control (Ctr). For the highest equal non-cytotoxic compound dilution tested at 48h cell treatment, total protein concentration was measured using a Pierce bicinchoninic acid (BCA) assay (n=3), and expression of 23 cytokines was analyzed using the Bio-Plex cytokine assay (n=2). Data were analyzed by one-way ANOVA and Tukey's test (α=5%).
RESULTS
The MTT assay revealed that at 24h and 48h, CHX and EGCG did not reduce cell metabolic activity at concentrations of 2.5-20μM (CHX) and 2.5-160μM (EGCG), respectively (p>0.05). At 48h, total protein levels were consistent across all groups for 20μM compound dilution (Ctr: 1.04mg/mL; CHX: 0.98mg/mL; and EGCG: 1.06mg/mL). At 20μM dilution, both CHX and EGCG significantly increased the secretion of IL-1β, IL-10, IL-12, KC, MIP-1α, IFN-γ and IL-6 (p<0.05). Treatment with CHX significantly increased secretion of IL-4 and RANTES (p<0.05).
TREATMENT
with EGCG significantly increased Eotaxin secretion (p<0.05). Both CHX and EGCG significantly decreased secretion of IL-17 (p<0.05). GM-CSF and TNF-α did not present significant change in secretion after treatment with either CHX or EGCG (p>0.05).
SIGNIFICANCE
Both CHX and EGCG modulate secretion of various inflammatory and anti-inflammatory mediators in odontoblastic cells.
Topics: Animals; Catechin; Cell Line; Chlorhexidine; Cytokines; Mice; Odontoblasts
PubMed: 29428678
DOI: 10.1016/j.dental.2018.01.025 -
Lasers in Medical Science Jan 2016Blue light emitting diodes (LEDs) are frequently used in dentistry for light activation of resin-based materials; however, their photobiostimulatory effects have not yet...
Blue light emitting diodes (LEDs) are frequently used in dentistry for light activation of resin-based materials; however, their photobiostimulatory effects have not yet been fully investigated. This study aimed to investigate the effect of blue LED (455 nm) on the metabolism of odontoblast-like cells MDPC-23. Energy doses of 2 and 4 J/cm(2) were used at 20 mW/cm(2) fixed power density. MDPC-23 cells were seeded at 10,000 cells/cm(2) density in Dulbecco's modified Eagle's medium (DMEM) containing 10 % fetal bovine serum (FBS). After 12 h, the culture medium was replaced with new DMEM supplemented with 0.5 % of FBS, and the cells were incubated for further 12 h. After that, single irradiation was performed to the culture, under selected parameters. Cell viability evaluations (Alamar Blue Assay, n = 12), number of viable cells (Trypan Blue Assay, n = 12), morphological analysis by scanning electron microscopy (SEM, n = 2), gene expression (n = 6) of alkaline phosphatase (Alp), collagen (Col-1a1), and dental matrix protein (Dmp-1) (quantitative polymerase chain reaction (qPCR)) were performed 72 h after irradiation. Data were analyzed by Kruskal-Wallis, ANOVA, and Tukey tests (p < 0.05). Direct light application at 4 J/cm(2) energy dose had no negative effects on cell viability, while irradiation with 2 J/cm(2) reduced cell metabolism. None of doses affected the number of viable cells compared with the control group. The two energy doses downregulated the expression of Alp; however, expression of Col-1a1 and Dmp-1 had no alteration. Cells presented change in the cytoskeleton only when irradiated with 2 J/cm(2). In conclusion, the blue LED (455 nm) irradiation, under the evaluated parameters, had no biostimulatory effects on MDPC-23 cells.
Topics: Alkaline Phosphatase; Animals; Cattle; Cell Line; Cell Survival; Gene Expression Regulation, Enzymologic; Light; Odontoblasts; Semiconductors
PubMed: 26608964
DOI: 10.1007/s10103-015-1837-z -
"Metabolism of Odontoblast-like cells submitted to transdentinal irradiation with blue and red LED".Archives of Oral Biology Nov 2017The present study evaluated the trans-dentinal effect of light emitting diodes (LEDs) irradiation on the metabolism of odontoblast-like cells.
OBJECTIVES
The present study evaluated the trans-dentinal effect of light emitting diodes (LEDs) irradiation on the metabolism of odontoblast-like cells.
METHODS
Seventy-two dentin discs (0.2mm thick) were obtained from human molar teeth. MDPC-23 cells (20,000 cells/disc) were seeded on the pulpal side of the discs using DMEM, supplemented with 10% fetal bovine serum (FBS). After 12h, the culture medium was replaced with DMEM containing 0.5% FBS. After additional 12h, blue (455±10nm) or red (630±10nm) LEDs were used at irradiances of 80 and 40mW/cm, respectively, to irradiate the occlusal side of the discs. The energy doses were fixed at 2 or 4J/cm. Cell viability, alkaline phosphatase activity (ALP), total protein production and collagen synthesis were evaluated 72h after irradiation. Data were submitted to Kruskal-Wallis and Mann-Whitney tests (α=0.05).
RESULTS
Red light promoted proliferative effects at the energy dose of 4J/cm Conversely, cell cultures irradiated with 2J/cm emitted by the blue light showed reduced viability. ALP production was stimulated by red light in comparison with blue light at 4J/cm. Total protein production was reduced after exposure to blue light at 4J/cm, while no effect was observed on collagen production.
CONCLUSIONS
Irradiation with red LED at 4J/cm bio-stimulated the viability of odontoblast-like cells, whilst blue light had unfavorable effects on the cellular metabolism.
Topics: Alkaline Phosphatase; Cell Line; Cell Proliferation; Cell Survival; Cells, Cultured; Collagen; Humans; Light; Molar; Odontoblasts
PubMed: 28841473
DOI: 10.1016/j.archoralbio.2017.08.004 -
FASEB Journal : Official Publication of... Feb 2021The objectives of our study were to investigate the roles of mTORC1 in odontoblast proliferation and mineralization and to determine the mechanism by which mTORC1...
The objectives of our study were to investigate the roles of mTORC1 in odontoblast proliferation and mineralization and to determine the mechanism by which mTORC1 regulates odontoblast mineralization. In vitro, MDPC23 cells were treated with rapamycin (10 nmol/L) and transfected with a lentivirus for short hairpin (shRNA)-mediated silencing of the tuberous sclerosis complex (shTSC1) to inhibit and activate mTORC1, respectively. CCK8 assays, flow cytometry, Alizarin red S staining, ALP staining, qRT-PCR, and western blot analysis were performed. TSC1-conditional knockout (DMP1-Cre ; TSC1 , hereafter CKO) mice and littermate control (DMP1-Cre ; TSC1 , hereafter WT) mice were generated. H&E staining, immunofluorescence, and micro-CT analysis were performed. Transcriptome sequencing analysis was used to screen the mechanism of this process. mTORC1 inactivation decreased the cell proliferation. The qRT-PCR and western blot results showed that mineralization-related genes and proteins were downregulated in mTORC1-inactivated cells. Moreover, mTORC1 overactivation promoted cell proliferation and mineralization-related gene and protein expression. In vivo, the micro-CT results showed that DV/TV and dentin thickness were higher in CKO mice than in controls and H&E staining showed the same results. Mineralization-related proteins expression was upregulated. Transcriptome sequencing analysis revealed that p53 pathway-associated genes were differentially expressed in TSC1-deficient cells. By inhibiting p53 alone or both mTORC1 and p53 with rapamycin and a p53 inhibitor, we elucidated that p53 acts downstream of mTORC1 and that mTORC1 thereby promotes odontoblast mineralization. Taken together, our findings demonstrate that the role of mTORC1 in odontoblast proliferation and mineralization, and confirm that mTORC1 upregulates odontoblast mineralization via the p53 pathway.
Topics: Animals; Cell Line; Cell Proliferation; Dentin; Mechanistic Target of Rapamycin Complex 1; Mice; Odontoblasts; Tooth Calcification; Transcriptome; Tuberous Sclerosis Complex 1 Protein; Tumor Suppressor Protein p53
PubMed: 33508145
DOI: 10.1096/fj.202002016R -
Medical Molecular Morphology Mar 2022Fibroblast growth factor 8 (FGF8) is known to be a potent stimulator of canonical Wnt/β-catenin activity, an essential factor for tooth development. In this study, we...
Fibroblast growth factor 8 (FGF8) is known to be a potent stimulator of canonical Wnt/β-catenin activity, an essential factor for tooth development. In this study, we analyzed the effects of co-administration of FGF8 and a CHIR99021 (GSK3β inhibitor) on differentiation of dental mesenchymal cells into odontoblasts. Utilizing Cre-mediated EGFP reporter mice, dentin matrix protein 1 (Dmp1) expression was examined in mouse neonatal molar tooth germs. At birth, expression of Dmp1-EGFP was not found in mesenchymal cells but rather epithelial cells, after which Dmp1-positive cells gradually emerged in the mesenchymal area along with disappearance in the epithelial area. Primary cultured mesenchymal cells from neonatal tooth germ specimens showed loss of Dmp1-EGFP positive signals, whereas addition of Wnt3a or the CHIR99021 significantly regained Dmp1 positivity within approximately 2 weeks. Other odontoblast markers such as dentin sialophosphoprotein (Dspp) could not be clearly detected. Concurrent stimulation of primary cultured mesenchymal cells with the CHIR99021 and FGF8 resulted in significant upregulation of odonto/osteoblast proteins. Furthermore, increased expression levels of runt-related transcription factor 2 (Runx2), osterix, and osteocalcin were also observed. The present findings indicate that coordinated action of canonical Wnt/β-catenin and FGF8 signals is essential for odontoblast differentiation of tooth germs in mice.
Topics: Animals; Cell Differentiation; Fibroblast Growth Factor 8; Mesenchymal Stem Cells; Mice; Odontoblasts; Osteoblasts
PubMed: 34739612
DOI: 10.1007/s00795-021-00297-3 -
The Anatomical Record Jun 1996Differentiation of odontoblasts involves cell-to-cell recognition, contact stabilization involving the formation of attachment specializations, cytoplasmic polarization,... (Review)
Review
Differentiation of odontoblasts involves cell-to-cell recognition, contact stabilization involving the formation of attachment specializations, cytoplasmic polarization, development of the protein synthetic and secretory apparatus, and the active transport of mineral ions. The secretory odontoblast is characterized by an extensive rough-surfaced endoplasmic reticulum, a highly developed Golgi complex, and the presence of specific secretion granules. Type I collagen, a major constituent of dentin matrix, appears to be secreted by the odontoblast into predentin at the proximal portion of the odontoblast process, the major cytoplasmic process extending from the odontoblast cell body into the dentin. The odontoblast process contains a rich network of microtubules and microfilaments. The proximal portion of the process is also a site of fluid-phase endocytosis. Adjacent odontoblasts are held together by numerous macula adherens junctions and a well-developed distal junctional complex adjacent to be predentin. Junctional strands of the occludens type have been observed to be a component of this junctional complex. Tracer studies employing horseradish peroxidase indicate that this junctional complex does not form a tight barrier to the diffusion of tissue fluid from the interodontoblast spaces into the predentin. Many well-developed gap junctions are formed between adjacent odontoblasts and between odontoblasts and the fibroblasts that make up the subodontoblastic layer. Ca-ATPase activity is demonstrated in the Golgi complex and mitochondrial cristae and along the distal plasma membranes of odontoblasts. ALPase activity is also intense along the entire odontoblast cell surface. The osmium tetroxide-pyroantimonate technique for calcium localization demonstrates prominent reaction precipitates in mitochondria of odontoblasts. Energy-dispersive x-ray microanalysis of anhydrously fixed and processed odontoblasts detected Ca and P peaks throughout the cytoplasm. A sulfur peak is noted in the distal cytoplasm of odontoblasts and in matrix vesicles. Together, these results demonstrate the complexity and variety of cell functions involved in dentinogenesis.
Topics: Animals; Calcium; Cell Communication; Cytoskeleton; Dentin; Dentinogenesis; Extracellular Matrix; Odontoblasts; Organelles; Rats; Tooth
PubMed: 8769666
DOI: 10.1002/(SICI)1097-0185(199606)245:2<235::AID-AR10>3.0.CO;2-Q -
Journal of Dentistry Feb 1995The value of the concept of a pulpo-dentinal complex was assessed on human teeth treated according to the ISO test on biological evaluation. The teeth were extracted... (Review)
Review
OBJECTIVES AND METHODS
The value of the concept of a pulpo-dentinal complex was assessed on human teeth treated according to the ISO test on biological evaluation. The teeth were extracted after 1 or 3 months and examined histologically. Biochemical and biological data available from the dental literature were also re-examined.
RESULTS
During the early development of the tooth, pulp and dentine establish close links and form an undivided organ. However, examination of the tissues at later stages of development casts doubt on the validity of such a concept. Major differences are reviewed in this report between the cells (odontoblasts and heterogeneous pulpal cells) and extracellular matrix (collagens, non-collagenic proteins and phospholipids) located either in the odontoblast-dentine area or in the pulp. It seems also that clear-cut differences are detected during inflammatory and repair processes.
CONCLUSION
It is concluded that, although the existence of a dentino-pulpal reaction cannot be denied, the concept of a pulpo-dentinal complex is an oversimplification and should be revisited. This may have implications in the evaluation of restorative treatments and in the design of a tissue repair strategy.
Topics: Adolescent; Adult; Child; Dental Pulp; Dentin; Dentin, Secondary; Extracellular Matrix; Humans; Odontoblasts; Odontogenesis
PubMed: 7876411
DOI: 10.1016/0300-5712(95)90655-2